What is it about?
We performed meta-analysis of continent-wide changes in body size and yellow carotenoid-based plumage coloration over 100 years in 15 species of Australian birds. Neither size nor colour showed a consistent temporal trend and changes in colour were not correlated with changes in size. This provides no evidence that broad-scale variation in food availability is a general explanation for continent-wide changes in body size in this group of species.
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Why is it important?
The research addresses the globally observed changes in the body sizes of organisms that are presumed to be occurring as a result of climate change or other broadscale environmental change. However, the causes of these body size changes remain largely mysterious partly due to the difficulty to reconstruct the past. Following a suggestion we made in a recent review on this topic (Gardner et al. 2011, Trends Ecol Evol 26:285–291), we use a novel approach based on carotenoid-based plumage colouration as preserved in museum specimens, utilising methods for objective assessment of plumage coloration on the scale of an avifauna that we have developed and proofed (Delhey et al. 2015, Delhey 2015).
Perspectives
We are testing whether recent, in the last 100 years, continent-wide changes in animal body size are associated with changes in environmental quality. As an indicator of this we are using yellow carotenoid-based plumage colour of museum specimens that is strongly dependent on food availability in the environment and body condition more generally. We measured plumage colour and body size over 100 years in 15 terrestrial Australian bird species from across their ranges, and found variation in magnitude and direction of change for colour as well as size. However, using phylogenetically-controlled meta-analyses we could detect no congruence in changes in body size and yellow plumage coloration. Therefore our study provides no support for the hypothesis that broad-scale size changes are related to changes in environmental food availability.
Anne Peters
Monash University
Read the Original
This page is a summary of: Are long-term widespread avian body size changes related to food availability? A test using contemporaneous changes in carotenoid-based color, Ecology and Evolution, March 2017, Wiley,
DOI: 10.1002/ece3.2739.
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